1. Field of the Invention
The present invention relates to a method of manufacturing a contact element and a multi-layered wiring substrate, both of which form part of a wafer batch contact board that can be used to check or test, within only one step, numerous semiconductor devices on a wafer.
2. Description of the Related Art
Testing or checking numerous semiconductor devices on a wafer may be generally divided into a product test (electric property test) carried out by means of a probe card, and a burn-in test for assuring reliability after the product test.
Here, the bum-in test is a sort of screening test for removing semiconductor devices with inherent defects, or devices which cause failure due to irregularity in manufacturing process and depending on time and stress. In fact, the burn-in test may be referred to as a heat accelerating test, which is different from the device electric property test using a probe card.
The burn-in test is usually conducted after the electric property test which is performed for each chip by means of a probe card. In the burn-in test, a wafer is cut into chips through dicing process, and the test is performed for each package containing the chips. Thus, such a burn-in test may be called one chip burn-in system and is high at its cost. In order to solve this problem, there has been developed and put into practical use a wafer batch contact board (burn-in board) which can be used to carry out a burn-in test of numerous semiconductor devices formed on a wafer (Japanese Unexamined Patent Application Publication No. 7-231019) in only one step. A wafer batch burn-in system using the wafer batch contact board is considered to be an important technique, since it can be carried out at a low cost and is useful for putting into practical use a recently developed new techniques called bare chip shipping and bare chip mounting.
The wafer batch contact board is different from a conventional probe card, since the wafer batch contact board has higher requirements than those of the conventional probe card. This is because the wafer batch contact board can be used to check numerous chips formed on a wafer in only one step and can also be used in a heating test. If the wafer batch contact board is put into practical use, it is possible to carry out, on the base of wafer batch, the product examination (electric property test) formerly conducted by means of a conventional probe card.
FIG. 1 is an explanatory view showing in detail an example of the wafer batch contact board.
The wafer batch contact board, as shown in FIG. 1, comprises a multi-layered wiring substrate 20 for use in a wafer batch contact board (hereinafter, it is simply referred to as multi-layered wiring substrate), and a contact element 10 fixed on the multi-layered wiring substrate 20 through an anisotropic electrically conductive rubber sheet 30.
The contact element 10 has a contact portion for directly contacting an examined element. Specifically, the contact element 10 is located in the vicinity of an insulating film (membrane) 12, on one side of which there are formed a plurality of bumps 13, on the other side of which there are formed a plurality of pads 14. In particular, the insulating film 12 is spread over a ring 11 having a low coefficient of thermal expansion so as to avoid a dislocation which will possibly be caused due to a thermal expansion. The bumps 13 are provided in positions corresponding to the pads formed on the edge or center lines of all semiconductor devices (chips) on the wafer 40 (one chip has approximately 600 to 1000 pins, so that the number of the pads formed on the wafer are equal to a number calculated by multiplying the above number of the pins with the total number of the chips). In this way, the same number of the bumps 13 are located in positions corresponding to the positions of the pads 14 (having the same number as the bumps 13).
The multi-layered wiring substrate 20 has a wiring structure formed on an insulating substrate for supplying a predetermined burn-in test signal through the pads 14 to various bumps 13 independently located on the membrane 12. However, since the wiring structure on the multi-layered wiring substrate 20 is relatively complex, a plurality of wiring layers have to be laminated one upon another through a plurality of commonly used insulating films. Further, the multi-layered wiring substrate 20 employs an insulating substrate having a low coefficient of thermal expansion, so that it is possible to avoid a connection failure which will otherwise be caused due to a positional deviation (caused by thermal expansion) relative to the pads 14 on the membrane 12.
The anisotropic electrically conductive rubber sheet 30 is made of an elastomer (consisting of a silicon resin, with metallic particles buried in the electrode portions of the pads along their electrically conducting directions) having an electric conductivity in only directions which are perpendicular to the main surface thereof. Specifically, the anisotropic electrically conductive rubber sheet 30 is connected with terminals (not shown) formed on the multi-layered wiring substrate 20 and the pads 14 formed on the membrane 12. In particular, the anisotropic electrically conductive rubber sheet 30, by virtue of projections (not shown) formed on the surface thereof, can get in contact with the pads 14 formed on the membrane 12, so that it is possible to absorb some concave and convex portions on the surface of the semiconductor wafer 40 and irregularities in the height of the bumps 13, thereby ensuring an exact connection between the pads formed on the semiconductor wafer and the bumps formed on the membrane 12.
A contact element partially forming the above-described wafer batch contact board, as shown in FIG. 2A, may be produced by at first forming a laminated body 4 including an insulating film 1 (made of polyimide or the like) and an electrically conductive layer 2 (made of copper or the like). Then, an excimer laser is used to perform a laser treatment to form a plurality of bump holes 1a extending from the surface of the insulating film 1 to the electrically conductive layer 2. Afterwards, one of plating electrodes is connected to the electrically conductive layer 2 so as to carry out an electrolytic plating of Ni or the like. In this way, as shown in FIG. 2B, the plating material will grow to fill the bump holes 1a, and once the plating material reaches the surface of the polyimide film 1, it will spread equally in every direction around each bump hole 1a, thereby forming a plurality of bumps 3 consisting of hard Ni alloy.
However, an insulating resin film usually has a water rejection property and thus is not easy to be wetted by water. Moreover, since each of the bump holes has an extremely small diameter and since the bump holes are considerably deep, it is difficult for the plating liquid to reach the bottom of each bump hole. If the plating liquid fails to completely fill the bump holes by arriving at the bottoms thereof, the desired bumps will not grow or the growth is not acceptable. As a result, products containing ungrown bumps or improperly grown bumps have to be deemed as defective products.
Moreover, in the case where the surface of the insulating film is difficult to be wetted by the plating liquid, air bubbles are likely to attach to the surface of the insulating film. In fact, such kind of air bubbles are not easy to be removed once they have attached to the surface of the insulating film. Consequently, if the bumps grow under a condition in which the air bubbles have been attached to the surface of the insulating film, some bumps in the vicinity of air bubbles will grow but will avoid air bubbles, hence causing defects such as deformed bumps.
In order to reduce ungrown bumps or improperly grown bumps and to reduce defects such as deformed bumps, there has been suggested an improved method which will be described in the following. Namely, before being dipped into a plating liquid, the laminated body 4 is at first dipped into a solvent (such as methanol) having a good wetability with respect to the insulating film. In this way, bump holes are at first filled with the solvent which is then replaced by the plating liquid.
However, although the use of the above method makes it possible to reduce the number of ungrown bumps or improperly grown bumps, it is still difficult to completely eliminate the above-described defective bumps. Another problem associated with the above method is that it involves a complex manufacturing process and hence production cost is high.
In order to solve the above problem, Japanese Unexamined Patent Application Publication No. 8-180757 has disclosed another technique requiring that the bump holes be subjected to an ozone treatment and/or an ultraviolet light treatment. However, the ozone treatment and/or ultraviolet light treatment have been found to provide only a weak effect but require a considerably long treatment time. For example, when a laser beam is used to form holes through the insulating layer (made of polyimide or the like), carbons generated due to laser ablation as well as the insulating layer itself will be melted and burned (carbonized). As a result, carbons such as xe2x80x9csootxe2x80x9d and xe2x80x9cdregsxe2x80x9d (decomposition products of the insulating layer, mainly containing black carbon) will easily get into and attach around the bump holes. At this time, even if the ozone treatment and/or ultraviolet light treatment are conducted continuously for 30 minutes, it is still almost impossible to remove the carbons such as xe2x80x9csootxe2x80x9d and xe2x80x9cdregsxe2x80x9d.
On the other hand, with regard to the contact holes formed in the multi-layered wiring substrate, some organic substances such as a residue of the insulating layer and a residue of a development liquid will remain within the contact holes, causing a decrease in the reliability of an electric connection formed through the contact holes. Consequently, the multi-layered wiring substrate has only a deteriorated yield.
In particular, with regard to the contact element and the multi-layered wiring substrate (both of which together form part of the wafer batch contact board), since each product involves a large number of holes, the above-described problems will reduce the yield of each product and increase the cost for manufacturing each product. Accordingly, there has been a strong demand to develop a new technique to solve the above problems.
It is a first object of the present invention to provide an improved method of manufacturing a contact element, which method is capable of completing a predetermined treatment within a shortened time and ensuring an increased treatment effect as compared with the ozone treatment and/or ultraviolet light irradiating treatment, in particular, capable of exactly eliminating in a short time carbons such as xe2x80x9csootxe2x80x9d and xe2x80x9cdregsxe2x80x9d generated and attached due to laser light irradiation. Therefore, when the bumps are subjected to plating treatment during the contact element manufacturing process, it is possible to exactly eliminate some defects such as deformed bumps caused due to the presence of the above-described carbons.
It is a second object of the present invention to provide a method of manufacturing a multi-layered wiring substrate having a high electric connection reliability obtainable through contact holes formed in the wiring substrate, thus enabling the multi-layered wiring substrate to have a high yield.
It is a third object of the present invention to provide a wafer batch contact board which has a high reliability and a high yield and can be produced at a low cost.
In order to achieve the above objects, the present invention has been accomplished as having the following constitutions.
According to a first aspect of the present invention, there is provided a method for manufacturing a contact element, comprising the steps of: forming a laminated body including an insulating film and at least one electrically conductive layer; forming, in the predetermined positions of the insulating film, bump holes extending from the surface of the insulating film to the at least one electrically conductive layer; performing surface treatment by carrying out a plasma treatment to treat the interior of the bump holes and/or the surface of the insulating film; and forming bumps on the bump holes treated in the surface treatment step.
According to a second aspect of the present invention, there is a method for manufacturing a contact element, comprising the steps of: forming a laminated body including an insulating film and at least one electrically conductive layer; forming, in the predetermined positions of the insulating film, bump holes extending from the surface of the insulating film to the at least one electrically conductive layer; performing surface treatment by carrying out an X-ray irradiation to treat the interior of the bump holes and/or the surface of the insulating film; and forming bumps on the bump holes treated in the surface treatment step.
According to a third aspect of the present invention, there is provided a method for manufacturing a contact element, wherein the bump holes are formed through a laser treatment.
According to a fourth aspect of the present invention, there is provided a method for manufacturing a contact element, wherein after the surface treatment performed by carrying out the plasma treatment and/or the X-ray irradiation to treat the interior of the bump holes and/or the surface of the insulating film, an oxide film removal treatment is carried out prior to an electrolytic plating or a non-electrolytic plating, for removing an oxide film of an electrically conductive layer exposed to the bottoms of the bump holes, followed by forming bumps on the bump holes through the electrolytic plating, with the electrically conductive layers serving as an electrode.
According to a fifth aspect of the present invention, there is provided a method for manufacturing a contact element, comprising a step of spreading the laminated body over a support frame.
According to a sixth aspect of the present invention, there is provided a method for manufacturing a multi-layered wiring substrate which is formed by at first laminating, on an insulating substrate material, a plurality of electrically conductive layers with an insulating layer interposed therebetween, then conducting the electrically conductive layers through a plurality of contact holes formed in the insulating layer, the method comprising a surface treatment which is effected by carrying out a plasma treatment to treat the interior of the contact holes and/or the surface of the insulating layer, in an atmosphere of a mixed gas formed by an oxygen gas and another containing halogen atoms in its molecules.
According to a seventh aspect of the present invention, there is provided a method for manufacturing a multi-layered wiring substrate which is formed by at first laminating, on an insulating substrate material, a plurality of electrically conductive layers with an insulating layer interposed therebetween, then conducting the electrically conductive layers through a plurality of contact holes formed in the insulating layer, the method comprising a surface treatment which is effected by carrying out an X-ray irradiation to treat the interior of the contact holes and/or the surface of the insulating layer.
According to an eighth aspect of the present invention, there is provided a method for manufacturing a multi-layered wiring substrate forming part of a wafer batch contact board which is for use in the batch examining of numerous semiconductor devices formed on a wafer, the method comprising the steps of: forming a first electrically conductive layer on an insulating substrate, patterning the first electrically conductive layer to form a first wiring pattern; forming an insulating layer on the first wiring pattern and forming contact holes in the insulating layer; performing a surface treatment which is effected by carrying out the plasma treatment or the X-ray irradiation to treat the interior of the contact holes and/or the surface of the insulating layer; and forming a second electrically conductive layer on an insulating substrate, patterning the second electrically conductive layer to form a second wiring pattern. In particular, a series of processes including the step of forming the insulating film and the contact holes, the step of performing the surface treatment and the step of forming the second wiring pattern are repeated at least once.
According to a ninth aspect of the present invention, there is provided a wafer batch contact board comprising: a contact element for use in a wafer batch contact board which is produced according to the method of the fifth aspect of the invention; and a multi-layered wiring substrate for use in a wafer batch contact board which is produced according to the method of the eighth aspect of the invention; and an anisotropic electrically conductive rubber for electrically connecting the multi-layered wiring substrate with the contact element.
According to the first and second aspects of the present invention, the use of the plasma treatment and/or X-ray (soft X-ray) irradiation is effective for removing in a short time the organic substances existing on the surface of the insulating film and/or within the bump holes. An effect obtained from such a treatment is highly acceptable.
Furthermore, using the plasma treatment and/or X-ray (soft X-ray) irradiation makes it possible to modify the surface of the insulating film and/or the internal surface of the bump holes. Therefore, it can be made exact for the plating liquid to more easily wet the surface of the insulating film and/or the internal surface of the bump holes. As a result, it becomes possible to greatly reduce ungrown bumps which will otherwise be caused due to incomplete filling of the bump holes with the plating liquid, as well as insufficient growth of bumps which will otherwise be caused due to insufficient filling of the bump holes with the plating liquid. Further, it is also possible to greatly reduce the defective contact points such as deformed bumps which will otherwise be caused due to a fact that during the plating treatment, air bubbles will adhere to the surface of the insulating resin layer adjacent to the bump holes.
Moreover, since the plasma treatment makes it possible to properly make rough the plated surface, it is possible for the plating liquid to more easily wet the plated surface.
Since the above effect has been proved to have a higher energy than an ultraviolet-ozone treatment using an ultraviolet-ozone treatment apparatus, a necessary time for carrying out the treatment of the present invention is allowed to be shortened to a great extent, thus improving the manufacturing efficiency.
According to the third aspect of the present invention, it is allowed to obtain the following effect. That is, when laser is used to perform laser treatment to form holes in the insulating film, although carbons will be generated during laser ablation and the insulating film will be melted and burned (carbonized) due to a heat and thus carbons such as xe2x80x9csootxe2x80x9d and xe2x80x9cdregsxe2x80x9d will occur and adhere to the internal surface of the bump holes and around the openings of these bump holes. However, such xe2x80x9csootxe2x80x9d and xe2x80x9cdregsxe2x80x9d can be completely removed in a short time by using the plasma treatment and/or X-ray (soft X-ray) irradiation of the present invention. As a result, during the step of bump plating for manufacturing the contact element, it can be made exact to prevent any defects such as deformed bumps which will otherwise be caused due to the above carbons. In this way, since the organic substances such as the above carbons may be completely removed, the wettability of the plating liquid can be improved when the above material is being wetted by the plating liquid and air bubbles can be prevented from occurring, thereby effecting an appropriate plating of the internal surface of the bump holes, as well as the desired formation of properly grown bumps. For this reason, the present invention is particularly useful for the case where a laser is used to perform a laser treatment to form holes in the insulating film.
Thus, when compared with the ultraviolet-ozone treatment using an ultraviolet-ozone treatment apparatus, the carbon removal treatment according to the present invention has been proved to be extremely effective for removing the carbons such as xe2x80x9csootxe2x80x9d and xe2x80x9cdregsxe2x80x9d. Further, a necessary time for carrying out the treatment is allowed to be shortened to an extremely large extent.
According to the fourth aspect of the present invention, since an oxide film removal treatment is carried out, prior to an electrolytic plating, for removing an oxide film of an electrically conductive layer exposed to the bottoms of the bump holes, it can be made sure to prevent a conduction failure which will otherwise be caused due to an oxide film formed on the exposed surface of the electrically conductive layer. Further, it is also possible to avoid the occurrence of some ungrown bumps or improperly grown bumps.
Moreover, since the positions of the bump holes will not be disturbed by a thermal expansion of the laminated body, it is allowed to produce a contact element having a high positional precision. In addition, since the bumps would have no positional deviations even if the contact element having a support frame will suffer from a thermal expansion, such a contact element can be suitably used to form a wafer batch contact board.
According to the sixth aspect of the present invention, since the plasma treatment is performed in an atmosphere of a mixed gas formed by an oxygen gas and another gas whose molecules contain halogen atoms, it is possible to inhibit an undesired etching of the insulating layer, also to inhibit an undesired build-up of some reaction products caused due to polymerization reaction.
Furthermore, since the plasma treatment can properly make rough the treated surface, the treated surface will have an improved combinability with an electrically conductive layer (it is allowed to expect an anchor effect).
However, operating conditions for the above treatment are allowed to be set in view of a real need, so that they may either be the same as or different from those for manufacturing the contact element.
According to the seventh aspect of the present invention, since an X-ray (soft X-ray) irradiation is carried out to treat the interior of the contact holes and/or the surface of the insulating layer, organic substances can be exactly removed, thereby making it possible to avoid a conduction failure caused due to contact holes, as well as an adhesion failure between an electrically conductive layer and the insulating layer.
Furthermore, since the X-ray (soft X-ray) irradiation can properly make rough the treated surface, the treated surface will have an improved combinability with an electrically conductive layer (it is allowed to expect an anchor effect).
However, operating conditions for the above treatment are allowed to be set in view of a real need, so that they may either be the same as or different from those for manufacturing the contact element.
According to the eighth aspect of the present invention, it is possible to obtain a multi-layered wiring substrate for use in a wafer batch contact board which has a high reliability as well as a high yield.
According to the ninth aspect of the present invention, since it is allowed to use a contact element and a multi-layered wiring substrate all having a high reliability as well as a high yield, it is possible to produce a wafer batch contact board which has a high reliability as well as a high yield, but can be manufactured at a low cost.